MM is a cancer of the plasma cells, causing the overproduction of a particular type of immunoglobulin; most commonly IgG. Around 20% of people with myeloma will overproduce only the light chain, which is termed light chain myeloma. Even less common is the production of little or no immunoglobulin, called non-secretory myeloma. The disease is characterized by the presence of abnormal antibodies in the serum or urine and increased plasma cells in the bone marrow. Patients with smoldering myeloma, an early form of MM, exhibit slightly increased levels of M protein and plasma cells, but a lack of the typical symptoms of MM.MM accounts for around 2% of all new cancer cases in the US and UK, and comprises approximately 10% of hematological malignancies. It typically affects more men than women and is more common in later life. The NIH reports that 49.6% of people diagnosed with MM survive for 5 years or more (based on data from SEER 18 2007-2013). Incidence rates of MM have gradually increased, for which many reasons could be speculated.As with many hematological cancers, the cause is unknown, but risk factors have been identified. These include exposure to radiation and certain chemicals, alcohol consumption, obesity and MGUS. MM can evolve from a premalignant condition known as monoclonal gammopathy of undetermined significance (MGUS).

MM is commonly treated with a combination of chemotherapy, steroids and ASCT. Exciting developments in this field include the use of MRD to guide treatment, monoclonal antibodies, CAR T-cells, upfront double ASCT and curative strategies for smoldering myeloma.